WHAT CAUSES CHANGES TO STREAM TEMPERATURES: LEVERAGING PUBLICLY AVAILABLE STREAM TEMPERATURE DATASETS TO INTERPRET DRIVERS OF SPATIO-TEMPORAL VARIABILITY (Invited Presentation)

Stream temperature is a powerful integrator and tracer of heat in natural and human-impacted systems. As it is closely tied to stream health, there is exceptional interest in assessing how stream temperatures are responding to changing climate as well as a host of human modifications. To date, studies have found both warming and cooling trends in waterways around the United States. Our work uses statistical analyses paired with trend assessments to parse the impacts of short term (e.g. drought) and long term (e.g., changing climate) variations on stream temperature. Sites include those experiencing extreme change due to humans and climate in California, as well as longer term records across the eastern United States. In particular, we show how human-impacted sites are shaped by dam release, while stream temperature at more natural sites responds to low summer streamflow. At longer timescales, we investigate several hypotheses for long term stream temperature change, and demonstrate how climate change and other human modifications are ultimately shaping long term trends in stream temperature.